Apparatus for adjusting the lateral position of a continuous moving web

ABSTRACT

APPARATUS IS PROVIDED FOR CONTROLLING THE LATERAL POSITION OF A CONTINUOUS WEB MOVING THROUGH A MACHINE SUCH AS A PRINTING PRESS. FIRST AND SECOND SPACED ROLLS ARE MOUNTED ON A CARRIAGE FOR ROTATION ABOUT PARALLEL AXES, WITH THE WEB LEAVING THE SECOND ROLL PARALLEL TO THE WEB ARRIVING AT THE FIRST ROLL. FLEXIBLE STRAPS SUPPORT THE CARRIAGE EACH STRAP BEING FLEXIBLE SUBSTANTIALLY ONLY NORMALLY OF THE PLANE INCLUDING THE RESPECTIVE STRAP AND THE LINE IN THE PLANE OF THE APPROACHING WEB TANGENT TO THE MID-POINT OF THE FIRST ROLL, THEREBY CONSTRAINING THE CARRIAGE TO ROTATION ABOUT THAT LINE AS A FIXED AXIS. EDGE DETECTORS SENSE THE LATERAL POSITION OF THE WEB AND PRODUCE A CONTROL SIGNAL USED TO DRIVE THE CARRIAGE ABOUT ITS AXIS TO CONTROL THE LATERAL POSITION OF THE WEB. THE EDGE DETECTORS MAY BE MOUNTED ADJACENT THE SECOND ROLL FOR ROTATION WITH THE CARRIAGE ABOUT A FIXED AXIS SUBSTANTIALLY COINCIDENT WITH THE MID-LINE OF THE LEAVING WEB TANGENT TO THE SECOND ROLL.

Oct. 26, 1971 J. R. MARTIN APPARATUS FOR ADJUSTING THE LATERAL POSITIONOF A CONTINUOUS MOVING WEB Filed April 5, 1969 3 Sheets-Sheet 1 FIG!FIG.3

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INVENTOR JOHN R. MARTIN %%M% Oct. 26,1971

Filed April 5, 1969 5 Sheets-Shoot 2 JOHN R. MARTIN WWW ATTYS Oct. 26,1971 J. R. MARTIN APPARATUS FOR ADJUSTING THE LATERAL POSITION OF ACONTINUOUS MOVING WEB Filed April 5, 1969 5 Sheets-Sheet 5 FIG] INVENTORJOHN R MOTOR CONTROL COMPARISON CIRCUIT W? ATTYS.

84 96 --IOO 3,615,048 APPARATUS FOR ADJUSTING THE LATERAL POSITION OF ACONTINUOUS MOVING WEB John R. Martin, Rockford, 11]., assignor to MartinAutomatic Incorporated, Rockford, Ill. Filed Apr. 3, 1969, Ser. No.813,110 Int. Cl. B6511 25/26 U.S. Cl. 226-20 10 Claims ABSTRACT OF THEDISCLOSURE Apparatus is provided for controlling the lateral position ofa continuous web moving through a machine such as a printing press.First and second spaced rolls are mounted on a carriage for rotationabout parallel axes, with the Web leaving the second roll parallel tothe web arriving at the first roll. Flexible straps support thecarriage, each strap being flexible substantially only normally of theplane including the respective strap and the line in the plane of theapproaching web tangent to the mid-point of the first roll, therebyconstraining the carriage to rotation about that line as a fixed axis.Edge detectors sense the lateral position of the web and produce acontrol signal used to drive the carriage about its axis to control thelateral position of the Web. The edge detectors may be mounted adjacentthe second roll for rotation with the carriage about a fixed axissubstantially coincident with the mid-line of the leaving web tangent tothe second roll.

This invention relates generally to apparatus for adjusting the lateralposition of a continuous web moving through a machine such as a printingpress over a plurality of web guides. As used herein the term web guiderefers to parts of such apparatus such as rolls or angle bars aroundwhich the web is Wrapped in changing the direction of the web path andthe lateral position of the web. Such usage is to be distinguished fromconventional terminology in which the entire apparatus for adjusting thelateral position of the web is called a web guide. More specifically,the invention relates to apparatus of the box tilt or step tilt typewherein the position of the pair of rolls relative to the rest of themachine is adjustable to direct the web laterally a desired amount.Still more particularly, the invention is directed to apparatus forcontrolling the lateral position of the web passing through the machineso as, for example, to permit accurate registration of printing on apaper web.

In the graphic arts and more particularly in the operation of printingpresses, it is frequently necessary or desirable that certain operationsbe performed upon a continuous moving web. For example, it is desirableand practically necessary that printing presses print in proper registryon a continuous paper web in order that the printed product may beefficiently cut and assembled in suitable form. Unfortunately, ithappens that a web becomes misaligned from time to time as it passesthrough a printing press. That is, the web may be displaced laterallyfrom its proper position, resulting in imprinting at the wrong place onthe sheet and consequent spoilage. This error in the lateral position ofthe web is known as a sidelay error. Such sidelay errors may occur frommisalignment of the machine or from defects in the paper. For example, asubstantial sidelay error may occur from a misaligned splice in thepaper web. It is desirable that these errors be corrected promptly towithin the required limit of accuracy, such as plus or minus 0.005 inch.Modern printing presses operate at substantial rates such as 1200 feet aminute, and it is United States Patent "ice desirable that any errors becorrected as promptly as possible to reduce spoilage. To this end, it isdesirable that the corrections be made automatically.

Lateral repositioning of a continuous Web has been performed with whatis known as a tilt box comprising a pair of parallel guide rolls overwhich the web is run and which function as web guides to guide thedirection of the web. The pair of rolls may be tilted, thus steering theweb and repositioning it laterally. For high speed operation, however,the friction and backlash of prior art tilt boxes has resulted inhunting or sluggishmenss, neither of which is acceptable for highaccuracy and correction rate.

Further, for accurate control it is necessary to sense the lateralposition of the web in order that exact correctioins for deviation fromthe desired position may be achieved. Sensing means have previously beenpositioned at the first fixed roll after tilt box. However, this hasnecessarily meant a substantial delay between the adjustment of the tiltbox and the sensing unit. This has necessitated sluggish operation orhas resulted in over correction, for unless sluggish the sensing unitwould continue to indicate a need for correction long after the tilt'box had completed the adjustment.

In accordance with the present invention, the tilt box is mounted in amanner substantially eliminating friction an backlash. The tilt box issupported by a plurality of straps, each of which flexes in onedirection only, this direction being normal to a respective planethrough the axis about which the tilt box is to tilt. Further, thesensing means of the present invention are disposed at the tilt box, andthe sensing means are mounted in a fashion compensating for measuringerrors as would occur from twisting of the web in the process of thetilt box correction.

It is therefore an object of the present invention to provide animproved apparatus for rapidly adjusting or controlling the lateralposition of a continuous moving web.

Another object of the invention is to provide such apparatus capable ofaccurate adjustment or control at high speed.

Still another object of the invention is to provide such apparatus withimproved mounting means reducing friction and backlash.

Still another object of the invention is to provide such apparatus withsensing means accurately sensing the lateral position of the web, suchsensing means being disposed adjacent the adjusting apparatus.

Other objects and advantages of the invention will become apparent fromthe following detailed description, particularly when taken withreference to the drawings in which:

FIG. 1 is a perspective view of a tilt box made in accordance with thepresent invention;

FIG. 2 is a diagrammatic plan view of the tilt box shown in FIG. 1,illustrating its rotational mounting;

FIG. 3 is another diagrammatic plan view of the tilt box shown in FIG.1, illustrating the mounting of the edge detectors;

FIG. 4 is a diagrammatic end view of the tilt box shown in FIG. 1,illustrating the relationship of the tilt box to a printing press;

FIG. 5 is a digrammatic end view of the apparatus of FIG. 1 as modifiedfor operation in a step tilt configuration;

FIG. 6 is a plan view of the tilt box shown in FIG. 1;

FIG. 7 is an end view of the tilt box shown in FIG. 1;

FIG. 8 is a bottom view of a portion of the tilt box shown in FIG. 1;and

FIG. 9 is a schematic illustration of the servo system used incontrolling the tilt box shown in FIG. 1.

A of side rails 18 and 20 and axles 22 and 24, the rolls 12 and 14 beingrotatably mounted on the axles 22 and 24, respectively. The carriage 16is supported from supports 26 and 28 by a plurality of straps 30, 32, 34and 36. These straps are long and thin and of substantial width. Theyare substantially planar. They are particularly strong in tension butwhen supported at their ends are extremely flexible in a directionnormal to their plane. They may for example, be formed of a stack of 10berryllium copper strips each about 0.01 inch thick by about 1 /2 incheswide. Each of the straps is rigidly fastened at one end to one of thesupports 26, 28 and at the other end of the carriage 16, and may be 6inches long between fastenings. These straps are not only relativelyinextensible but they are extremely stiff in their lateral direction.The straps are mounted in such a way that they lie in respective planesintersecting along a line extending substantially in the direction ofmotion of the approaching webs. This is best illustrated in FIGS. 2 and3. As shown in FIG. 2, the straps 30 and 32 lie in a plane 38. Strap 34lies in a plane 40, and strap 36 lies in a plane 42. These planesintersect in a line 44 which is tangent to the roll 12 at its mid-point.The straps extend longitudinally generally parallel to the line 44 andare flexible in a directional normal to their respective planes, thuspermitting limited rotation of the carriage 16 about the line 44 as afixed axis. In FIG. 3, the displacement of the tilt box 10 about theline 44 as an axis is illustrated by dashed lines.

The supports 26 and 28 are mounted to the printing 'press to dispose therolls 12 and 14 as guide rolls in the path of a paper web 46 to contactthe paper web and guide it, the web 46 being a continuous web moving inthe direction indicated by the arrow 48. The tilt box 10 is mounted inrespect to the printing press in such manner that the web 46 as itleaves the second roll 14 is parallel to the web as it approaches theroll 12. This is achieved by appropriately disposing the rolls 12 and 14in respect to the regular rolls 50 and 52 of the press. Thus the paperweb leaves the roll 50, passes over the roll 12, then over the roll 14and then back to the roll 52, the web between rolls 14 and 52 beingparallel to the web between rolls 50 and 12. Further the tilt box 10 ismounted in such relationship to the printing press that the web 46 as itapproaches roll 12 is tangent to the center of the roll 12 along theline 44.

The arrangement of the tilt box 10 relative to a printing press is shownin FIG. 1 in what is known as a box configuration, whence the name tiltbox or box tilt originated. This is best illustrated in FIG. 4 which isa diagrammatic end view of the tilt box of FIG. 1, showing thedisposition of the tilt box rolls 12 and 14 relative to the rolls 50 and52 of the press and the manner in which the paper web 46 passes overthese rolls. As shown, the paper turns an angle of approximately 90 ateach of rolls 12 and 14, moving between rolls 12 and 14 in a planenormal to the planes of the web as it travels toward roll 12 and awayfrom roll 14.

One of the advantages of the tilt box of the present invention is thatit may be mounted in various configurations on existing presses, Forexample, in FIG. is illustrated an alternative configuration, where therolls 12 and 1-4 are not horizontal and wherein the Web 46 comes down toroll 12 from above to form What is called a step configuration. In theconfiguration of FIG. 5, the tension in the web 46 supports the roll 12,and the straps supporting the carriage 16 near roll 12 extend upwardlyfrom the supports 26 and 28 to the carriage 16, yet remain in tension.The step tilt configuration of FIG. 5 works in principle exactly likethe box tilt configuration of FIG. 4.

The printing on the web 46 is subsequent to the roll 52. It is thepurpose of the tilt box to direct the paper 4 onto roll 52 at suchlateral position as to cause proper registry of the printing on the Web.To this end, the tilting of the tilt box, that is its angular positionabout the axis 44, is adjustable. Although manual adjustment of theposition would be possible, in the apparatus as illustrated, adjustmentis effected by energizing an electric motor 54 which operates through agear box 56 to move a crank 58 which pulls or pushes a connecting rod60. As shown, the motor 54, gear box 56 and crank 58 are mounted on thecarriage 16. One end of the connecting rod is fastened to the crank 58,whereas the other end is fastened to the support 28. Thus when the motoris energized the crank 58 pulls or pushes the connecting rod 60 to movethe carriage relative to the support 28, hence moving the tilt box 10about the axis 44 relative to the rolls 50 and 52, which are secured tothe printing press. Although the motor 54 may be energized in theappropriate direction by the manual operation of an electric switch, inthe preferred embodiment of the present invention, an automatic controlis provided.

The automatic control, as illustrated, includes edge detectors 62 and 64mounted adjacent and just following the roll 14 at the edges of thepaper web 46. These edge detectors are mounted on rods 66 and 68 whichare fastened to a frame 70 comprising blocks 72 and 74 connected by abar 76. The frame 70 is supported from supports 26 and 28 by straps 78and 80 which may be made like straps 30, 32, 34 and 36 and attached attheir respective ends. The frame 70 is fastened to the carriage 16 bystraps 82 and 84 which may also be, like the other straps, flexible onlynormal to their flat sides. The effect of this mounting is to cause theframe 70 to move angularly with the rotation of the tilt box 10.However, because the straps 78 and 80 are flexible only in a directionparallel to the planes of supports 26 and 28, the frame 62 rotates aboutan axis between the straps 78 and 80'. To define this axis moreaccurately a post 86 is aifixed to the bar 78 and extends upwardly abovethe roll 14. An arm 88 extends from the post 86 and terminates at apivot 90 which is along the mid-line of the paper web 46 in its desiredposition as it leaves the roll 14. A connecting rod 92 is connectedbetween the pivot 90 and the support 26. The connecting rod 92, pivot90, arm 88 and post 86 accurately define the axis of rotation 91 of theframe 70 to be along the mid-line of the Web in its desired position asit leaves the roll 14.

The advantages of this arrangement will be apparent from considerationof FIG. 3. As was stated above, it has been known to mount edgedetectors near the fixed roll 52 of the press. This has thedisadvantage, as mentioned, that it takes a substantial time for the web46 to travel from the guide roll 14 to the fixed roll 52. Thisnecessarily results in a delay between the time the correction is madeat the roll 14 and when it is appreciated at the roll 52. Under suchcircumstances, if the control system responds rapidly to a positionerror noted at the roll 52, the tilt box 10 will overcorrect, for itwill continue to demand a correction until the proper position is notedat the roll 52, by which time the web 46 at the roll 14 will have gonebeyond the desired position. On the other hand, if the response of thecontrol system is damped to prevent overcorrection, the control issluggish and excessive spoilage results. Therefore, in the presentinvention the edge detectors are mounted adjacent the roll 14 Where thecorrection is made. This, however, creates other problems which are metby the particular mounting of the present invention, as will beexplained further below.

The edge detectors 62 and 64 may each comprise a lamp 94 of fixedintensity and a photosensitive detector 96 disposed on respective sidesof the web 46. Each edge detector is mounted adjacent a respective edge,the web moving between the lamp 94 and photosensitive detector 96. Eachedge detector detects the position of the edge by the amount of lightfrom the lamp reaching the photosensitive detector. The photosensitivedetector 96 then provides a detection signal indicative of the positionof the edge. It is desirable that the lamp 94 and photosensitivedetector 96 be relatively close together to assure high accuracy. Thefarther apart the lamp and photosensitive detector, the greater theuncertainty of measurement of the edge.

It may be noted in FIG. 3 that upon movement of the tilt box the web 46is twisted as well as moved laterally. Because of this twisting, theedge would not move directly in and out of the space between the lampand photosensitive detector were it not that the frame 70 twists aswell. At the same time, of course, the edge detector must not movelaterally with the roll 14, or it would not be able to sense theposition of the edge of the web relative to the press. The frame 70 istherefore mounted to move angularly about the axis 91, in unison withthe angular movement of the tilt box 10, but it is laterally constrainedrelative to the supports 26 and 28, as illustrated more particularly inFIG. 3. This permits the lamp 94 and photosensitive detector 96 of eachedge detector 62 or 64 to be disposed close together.

This position of the edge detectors 62 and 64 has the additional featurethat it corrects for foreshortening of the Web. That is, the projectionof the Web is foreshortened as the web twists; however, with the frame70 twisting with the web, the distance between edge detectors is equallyforeshortened, thus compensating for any foreshortening error. This isparticularly useful when but a single edge detector is used.

FIGS. 6, 7 and 8 illustrate the tilt box shown in FIG. 1 in greaterdetail, although more detailed Written description of the constructionis believed unnecessary.

In FIG. 9, the control circuit for the tilt box is illustrated inschematic and diagrammatic form. The control circuit is in large measurea conventional servo-mechanism circuit. Each of the edge detectors 62and 64 develops a signal indicative of the position of the respectiveedge of the web 46. The respective photosensitive detectors 96 producecorresponding detection signals which are applied over conductors 98 and100 to a comparison circuit 102. The comparison circuit 102 may beconventional circuit, such as a differential amplifier, which producesan error signal or a control signal indicative of the difference betweenthe signals appearing On detectors 98 and 100. The control signal thusprovides an indication of how much nearer one edge of the web 46 is toone edge detector than the other edge of the web is to the other edgedetector. This control signal is applied over a conductor 104 to a motorcontrol circuit 106 which operates in a conventional manner to supplyappropriate power over conductors 108 to drive the motor 54 in onedirection or another, depending upon the sense of the control signal.The motor 54 is driven in such direction as to tilt the tilt box 10 tomove the web 46 in the direction that reduces the difference in thedetection signals appearing on conductors 98 and 100. This then resultsin the centering of the web 46 along the axis 91, thus controlling thelateral position of the web to keep the web 46 in registry for printing.

In the foregoing description and in the claims, where the carriage axisis referred to as being along a line tangent to the mid-point of thefirst roll 12, it is intended to include the point where the center lineor mid-line of the approaching web is to contact the roll 12. Where theframe axis is referred to as being along the mid-line of the lea-vingweb, it is intended to refer to the mid-line of the web when the web isin its desired lateral position.

Although an exemplary embodiment of the invention has been shown anddescribed, various modifications in the apparatus may be made within thespirit and scope of the invention. For example, rather than providingtwo edge detectors and centering the web, it is possible to utilize buta single edge detector and maintain the edge of the web a predetermineddistance from the single edge detector. In such case, the comparisoncircuit 102 may receive a detection signal from only the one edgedetector, and a standard reference signal may be applied to thecomparison circuit in lieu of the other detection signal.

Also, under some conditions it is desirable to provide a balanced motordrive. In such instances, the shaft driving the crank 58 may be extendedacross the carriage to a bearing afiixed to the side rail 20, andanother crank may be fastened to the shaft to operate another connectingrod connected to the support 26.

It is also often desirable to make the position of the edge detectors 62and 64 adjustable on the rods 66 and 68. This may be achieved byconventional clamping means.

A fine adjustment of position may be achieved electronically in thecontrol unit.

It should also be clear that conventional power supplies are providedwhere needed.

Various of the features believed to be novel are set forth in theappended claims.

What is claimed is:

1. Apparatus for adjusting the lateral position of a continuous webmoving longitudinally along a path in a machine such as a printingpress, said apparatus comprising a rigid carriage, first and second webguides mounted on said carriage parallel to one another in laterallyspaced relationship, carriage mounting means for mounting said carriagerelative to said machine with said first and second web guides extendingtransversely of the web and with the web in contact first with saidfirst web guide and thereafter with said second web guide and leavingsaid second web guide substantially parallel to the web arriving at saidfirst web guide, said carriage mounting means including a plurality ofmounting members attached to said carriage and extending therefrom inrespective planes substantially normal to a plane perpendicular to theapproaching web and intersecting in a line in the plane of theapproaching web tangent to the mid-point of said first web guide andextending in the direction of motion of the approaching Web, one end ofeach mounting member being constrained to move relative to the othersubstantially only normally of said respective planes, therebyconstraining said carriage to limited rotation about said tangent lineas a substantially fixed carriage axis, and means for rotating saidcarriage about said carriage axis, there-by adjusting the lateralposition of the web leaving said second web guide.

2. Apparatus for adjusting the lateral position of a continuous webmoving longitudinally along a path in a machine such as a printingpress, said apparatus comprising a rigid carriage, first and secondrolls rotatably mounted on said carriage in laterally spacedrelationship for rotation about respective parallel axes, carriagemounting means for mounting said carriage relative to said machine withsaid parallel axes extending transversely of the web and With the web incontact successively with said first and second rolls and leaving saidsecond roll substantially parallel to the web arriving at said firstroll, said carriage mounting means including a plurality of flexiblestraps each afiixed at one end to said carriage and extending from saidcarriage substantially normally of a plane perpendicular to theapproaching web, said straps lying in respective planes intersectingalong the line in the plane of the approaching web tangent to themid-point of said first roll in the direction of motion of the web, saidstraps each being flexible substantially only normally of the respective one of said planes, thereby constraining said carriage tolimited rotation about said line as a substantially fixed carriage axis,and means for rotating said carriage about said carriage axis, therebyadjusting the lateral position of the web leaving said second roll.

3. Apparatus for controlling the lateral position of a continuous webmoving longitudinally along a path in a machine such as a printingpress, said apparatus comprising a rigid carriage, first and secondrolls rotatably mounted on said carriage in laterally spacedrelationship for rotation about respective parallel axes, carriagemounting means for mounting said carriage relative to said machine withsaid parallel axes extending transversely of the Web and with the web incontact successively with said first and second rolls and leaving saidsecond roll substantially parallel to the web arriving at said firstroll, said carriage mounting means including a plurality of flexiblestraps each affixed at one end to said carriage and extending from saidcarriage substantially normally of a plane perpendicular to theapproaching web, said straps lying in respective planes intersectingalong the line in the plane of the approaching web tangent to themid-point of said first roll in the direction of motion of the web, saidstraps each being flexible substantially only normally of the respectiveone of said planes, thereby constraining said carriage to limitedrotation about said line as a substantially fixed carriage axis, meansfor sensing the deviation of the lateral position of the web leavingsaid second roll from a predetermined position and producing a controlsignal indicative of such deviation, and motive means responsive to saidcontrol signal for rotating said carriage about said carriage axis inthe direction reducing said deviation, thereby controlling the lateralposition of the web leaving said second roll.

4. Apparatus according to claim 3 wherein the web path between saidfirst and second rolls is in a plane perpendicular to said line.

5. Apparatus for controlling the lateral position of a continuous webmoving longitudinally along a path in a machine such as a printingpress, said apparatus comprising a rigid carriage, first and second webguides mounted on said carriage parallel to one another in laterallyspaced relationship, caniage mounting means for mounting said carriagerelative to said machine with said first and second web guides extendingtransversely of the web and with the web in contact first with saidfirst web guide and thereafter with said second web guide and leavingsaid second web guide substantially parallel to the web arriving at saidfirst web guide, said carriage mounting means constraining said carriageto rotation about a substantially fixed carriage axis substantiallycoincident with the line in the plane of the approaching web tangent tothe midpoint of said first web guide in the direction of motion of theweb, a frame, connecting means connecting said frame to said carriagefor angular movement therewith, means for constraining said frame tomove substantially only in rotation about a substantially fixed frameaxis substantially coincident with the mid-line of the leaving webtangent to said second Web guide, sensing means for sensing the positionof at least one edge of the web and producing a control signalindicative of such position, said sensing means being mounted on saidframe for rotation therewith about said frame axis adjacent at least oneedge of said web as it leaves said second web guide, and motive meansresponsive to said control signal for rotating said carriage about saidgafrriage axis, thereby controlling the lateral position of th e"webleaving said second Web guide.

'6. Apparatus according to claim 5 wherein said sensing means comprisesfirst and second edge detectors each mounted on said frame adjacent saidsecond web guide for sensing the position of a respective edge of the.web by producing respective detection signals indicative thereof, andmeans for differentially combining said detection signals to derive saidcontrolsignal, and wherein said motive means responds to said controlsignal by rotating said carriage in the direction balancing saiddetection signals, thereby centering the web between said first andsecond edge detectors.

'7. Apparatus according to claim 5 wherein said sensing means comprisesan edge detector mounted on said frame adjacent said second web guidefor sensing the position of one edge of said web by producing adetection signal indicative thereof, means for developing a referencesignal, and means for comparing said detection and reference signals toproduce a control signal indicative of their difference, and whereinsaid motive means responds to said control signal by rotating saidcarriage in the direction reducing said control signal.

8. Apparatus according to claim 5 wherein said sensing means comprises aconstant intensity lamp and a photosensitive detector disposed onrespective sides of the path of said web.

9. Apparatus for controlling the lateral position of a continuous webmoving longitudinally along a path in a machine such as a printingpress, said apparatus comprising a rigid carriage, first and secondrolls rotatably mounted on said carriage in laterally spacedrelationship for rotation about respective parallel axes, carriagemounting means for mounting said carriage relative to said machine withsaid parallel axes extending transversely of the web and with the web incontact successively with said first and second rolls and leaving saidsecond roll substantially parallel to the web arriving at said firstroll, said carriage mounting means including a plurality of flexiblestraps each affixed at one end to said carriage and extending from saidcarriage substantially normally of a plane perpendicular to theapproaching web, the lateral direction of respective ones of said strapslying in respective planes intersecting along the line in the plane ofthe approaching web tangent to the mid-point of said first roll in thedirection of motion of the web, said straps each being flexiblesubstantially only normally of the respective one of said planes,thereby constraining said carriage to limited rotation about said lineas a substantially fixed carriage axis, a frame, connecting meansconnecting said frame to said carriage for angular movement therewith,means for constraining said frame to move substantially only in rotationabout a substantially fixed frame axis substantially coincident with themid-line of the leaving web tangent to said second roll, sensing meansfor sensing the position of at least one edge of the Web and producing acontrol signal indicative of such position, said sensing means beingmounted on said frame for rotation therewith about said frame axisadjacent at least one edge of said web as it leaves said second roll,and motive means responsive to said control signal for rotating saidcarriage about said carriage axis, thereby contrrilling the lateralposition of the Web leaving said second ro l. e

10. Apparatus for adjusting the lateral position of a continuous webmoving longitudinally along a path in a machine such as a printingpress, said apparatus comprising a rigid carriage, first and second webguides mounted on said carriage parallel to one another in laterallyspaced relationship, carriage mounting means for mounting said carriagerelative to said machine with said first and second web guides extendingtransversely of the web and with the web in contact first with saidfirst web guide and thereafter with said second web guide and leavingsaid second web guide substantially parallel to the' web arriving atsaid first Web guide, said carriage mounting means including a pluralityof mounting members attached to said carriage and extending therefromsubstantially normally of a plane perpendicular of the approaching web,one end of each mounting member being constrained to move relative tothe other end of said mounting member substantially only normally of arespective plane, said respective planes intersecting in a lineextending substantially in the direction of motion of the approachingweb, thereby constraining said carriage to limited rotation about saidline as a substantially fixed carriage axis, and means for rotating saidcarriage about said carriage axis, thereby adjusting the lateralposition of the web leaving said second web guide.

References Cited UNITED STATES PATENTS 3,373,288 3/1968 Otepka et al226-21 X RICHARD A. SCHACHER, Primary Examiner G. A. CHURCH, AssistantExaminer

